REINFORCED 

CONCRETE 

CODE 


CITY  OF  COLUMBUS 
OHIO 


DEPARTMENT  OF 
BUILDINGS 


Reinforced 
Concrete  Code 


* 


AN  ORDINANCE  No.  27098 

To  define  'and  describe  the  term  and  meaning 
of  reinforced  concrete  construction  and  to 
regulate  the  manner  of  its  use  in  building 
operations. 

Be  it  Ordained  by  the  Council  of  the  City  of 
Columbus,  State  of  Ohio: 

Section  1.  Definition.  By  the  term  Rein- 
forced Concrete  in  these  regulations  is  meant 
an  approved  structural  combination  of  concrete 
and  steel,  so  arranged  that  the  steel  resists  all 
the  tensile  stresses  and  may  aid  the  concrete  in 
resisting  shear  and  compression.  No  system 
of  reinforced  concrete  design  shall  be  used 
which  is  not  capable  of  design  and  investiga- 
tion according  to  the  best  engineering  practice, 
and  the  principles  laid  down  in  this  code. 

Sec.  2.  Requirements  for  Permit.  Before  a 
permit  to  erect  any  reinforced  concrete  struc- 
ture is  granted,  complete  plans  and  specifica- 
tions showing  all  details  of  construction,  the 
size  and  position  of  all  reinforcing  members  and 
the  composition  of  the  concrete  shall  be  sub- 
mitted to  the  Department  of  Buildings.  The 
Department  of  Buildings  reserves  the  right  to 
demand  that  the  owner,  architect  or  engineer 
submit  certified  copies  of  all  computations  or 
stress  sheets  for  examination  upon  application 
for  a building  permit. 

Permission  to  erect  any  reinforced  concrete 

3 


structure  does  not  in  any  way  approve  the  con- 
struction until  after  tests  have  been  made  of 
the  actual  construction  to  the  satisfaction  of 
the  Department  of  Buildings. 

Sec.  3.  Unit  Stresses.  The  following  unit 
stresses  shall  not  be  exceeded: 

Medium  steel,  16,000  lbs.  per  sq.  in. 

High  carbon  steel,  18,000  lbs.  per  sq.  in. 

Steel  to  resist  diagnoal  tension,  12,000  lbs. 
per  sq.  in. 

Concrete,  extreme  fiber  in  compression,  700 
lbs.  per  sq.  in. 

Bond  stresses  for  plain  round  bars,  70  lbs.  per 
sq.  in. 

Bond  stresses  for  twisted  bars  or  deformed 
bars,  100  lbs.  per  sq.  in. 

Concrete  in  shear,  50  lbs.  per^q.  in. 

Sec.  4.  Assumptions.  The  following  as- 
sumptions shall  be  made  as  a basis  for  the  cal- 
culation of  girders,  beams  and  slabs : 

(a)  The  stress  strain  curve  of  concrete  in 
compression  is  a straight  line. 

(b)  The  modulus  of  elasticity  of  concrete 
remains  constant  within  the  limits  of  unit 
working  stresses  specified  in  this  ordinance. 

(c)  The  adhesion  between  concrete  and  steel 
is  sufficient  to  make  the  two  materials  act 
together. 

(d)  Concrete  has  no  value  in  tension. 

(e)  The  ratio  of  the  modulus  of  elasticity  of 
steel  to  the  modulus  of  elasticity  of  concrete 
is  15. 

Sec.  5.  Slabs,  Beams  and  Girders.  Slabs, 
beams  and  girders  with  uniform  distribution  of 
load  shall  be  calculated  as  follows:  When  sim- 
ply supported  the  moment  equals  WL/8;  when 
continuous  over  one  support  the  moments  shall 

4 


be  considered  as  WL/10  at  center  and  WL/8 
over  intermediate  support;  when  continuous 
over  two  or  more  supports  with  equal  or  ap- 
proximately equal  spans,  the  moments  shall  be 
considered  as  WL/12  at  center  and  over  sup- 
ports of  intermediate  spans,  and  WL/10  at  cen- 
ter of  end  span  and  over  second  support;  where 
“W”=total  load  and  “L”=span  in  feet. 

In  continuous  slabs,  beams  and  girders,  with 
uniform  distribution  of  load,  continuity  rein- 
forcing shall  extend  over  and  beyond  supports 
at  least  one-fourth  (J4)  of  the  adjoining  span. 

Concentrated  loads  shall  be  computed  accord- 
ing to  accepted  theory,  and  in  the  case  of  con- 
tinuous spans  proper  provisions  shall  be  made 
for  continuity. 

For  slabs,  beams  and  girders  the  span  shall 
be  taken  as  the  distance  from  center  to  center 
of  supports,  but  need  not  exceed  the  clear 
span  plus  the  depth  of  slab,  beam  or  girder. 

"Sec.  6.  Tee-Beams.  Where  beams  are 
made  monolithic  with  the  floor  slab,  with  the 
slab  reinforcing  at  right  angles  to  the  beam, 
the  slab  may  be  considered  as  acting  in  flex- 
ture  with  the  beam,  provided  the  width  of 
slab  so  considered  be  governed  by  the  shear- 
ing resistance  between  the  slab  and  beam,  but 
be  limited  on  either  side  of  the  beam  to  1/6 
of  the  span  of  the  beam  between  supports  and 
also  limited  on  either  side  of  the  beam  to  five 
(5)  times  the  thickness  of  the  slab.  In  case 
the  reinforcing  is  not  at  right  angles  to  the 
beam,  the  portion  of  the  slab  so  considered 
shall  be  limited  on  either  side  of  the  beam 
to  three  (3)  times  the  thickness  of  the  slab. 
In  no  case  shall  the  total  width  of  flange  so 
taken  exceed  the  distance  center  to  center  , of 
beams. 

No  part  of  the  slab  shall  be  considered  as  a 

5 


portion  of  the  beam  unless  the  slab  and  beam 
are  cast  at  the  same  time. 

Where  reinforced  concrete  girders  support 
reinforced  concrete  beams,  the  portion  of  the 
floor  slab  acting  as  flange  to  the  girder  must 
be  reinforced  with  rods  near  the  top,  at  right 
angles  to  the  girder,  to  enable  it  to  transmit 
local  loads  directly  to  the  girder  and  not 
through  the  beams. 

In  tee-beams  construction  the  bottom  of  the 
web  over  continuous  supports  shall  be  pro- 
vided with  haunches,  or  be  reinforced  with 
sufficient  steel  in  compression,  to  reduce  the 
stress  on  the  concrete  to  within  ten  per  cent 
of  that  allowed  at  the  center  of  the  span.  This 
steel  shall  project  at  least  twenty-four  inches 
on  each  side  of  supports  and  the  unit  com- 
pressive stress  in  the  steel  shall  not  exceed 
fifteen  (15)  times  the  unit  compressive  stress 
in  the  concrete  at  the  same  distance  from  the 
neutral  axis. 

Sec.  7.  Square  and  Rectangular  Slabs.  For 

square  slabs  reinforced  in  both  directions  the 
moments  for  each  set  of  reinforcing  in  the 
center  half  of  the  slab  shall  be  taken  not  less 
than  WL  2/16  where  the  slab  under  considera- 
tion is  not  continuous;  WL2/20  where  the 
slab  under  consideration  is  continuous  over 
one  support,  and  WL2/24  at  center  and  over 
supports  where  the  slab  is  continuous  over 
both  supports;  where  “W”=the  load  per 
square  foot  and  “L”=side  of  square  in  feet. 
The  steel  in  the  remaining  quarters  may  be 
proportioned  by  using  one-half  of  the  amount 
used  in  the  middle  half. 

For  rectangular  slabs,  with  equal  spacing  of 
reinforcing  in  each  direction,  the  transverse 
reinforcing  shall  be  proportioned  to  carry  the 

6 


j 


amount  of  load  given  by  the  following 
formula : 

Wa4 

w= 

a4+b4 

Where  “w”==load  per  square  foot  carried  by 
the  transverse  reinforcing. 

“W”=total  load  per  square  foot  of  slab. 

“a”=length  of  slab  and 

“b”=breadth  of  slab. 

The  moments  in  the  central  half  of  the  slab 
for  the  transverse  reinforcement  shall  be  not 
less  than  wa2/8  where  the  slab  is  not  contin- 
uous, wa2/10  where  the  slab  is  continuous 
over  one  support,  and  wa2/12  at  center  and 
over  supports  where  the  slab  is  continuous 
over  both  supports.  The  steel  in  the  remain- 
ing quarters  may  be  proportioned  by  using 
one-half  (J4)  the  amount  used  in  the  middle 
half.  Where  the  length  of  a rectangular  slab 
exceeds  one  and  one-half  (1J4)  times  the 
breadth,  the  load  shall  be  assumed  to  all  be 
carried  by  the  transverse  reinforcement. 

The  amount  of  load  carried  to  the  side  beams 
for  square  and  rectangular  slabs  shall  be  taken 
according  to  the  above  assumptions  and  mo- 
ments, as  derived  by  the  assumption  of  uniform 
distribution  of  load,  shall  be  increased  twenty- 
five  (25)  per  cent. 

Sec.  8.  Minimum  Thickness  of  Slabs.  Re- 
inforced concrete  slabs  shall  not  be  less  than 
four  (4)  inches  thick  for  floors,  and  three  and 
one-half  (3/4)  inches  for  roofs  in  beams  and 
girder  construction,  except  in  spans  of  six  feet 
or  under,  in  which  case  the  above  thicknesses 
may  be  decreased  one-half  (J4)  inch,  provided 
the  unit  stresses  as  herein  given  are  not  efcc- 

7 


ceeded.  Slabs  shall  not  be  less  than  two  (2) 
inches  thick,  with  reinforcing  at  right  angles 
to  the  beam,  for  floors  using  beams  spaced 
close  together  and  separated  by  hollow  tile  or 
other  centering  or  fillers  satisfactory  to  the 
Inspector  of  Buildings. 

Sec.  9.  Reinforced  Terra  Cotta  Hollow  Tile. 

(a)  By  reinforced  terra  cotta  tile  is  meant  a 
system  of  hollow  burned  clay  tile  in  combina- 
tion with  reinforced  concrete,  in  which  combi- 
nation the  hollow  tile  may  be  used  to  resist 
compressive  and  shearing  stresses,  subject  to 
the  following  provisions : 

The  provisions  relating  to  reinforced  con- 
crete construction  shall  hold  as  far  as  appli- 
cable to  this  system. 

All  tile  to  be  hard  burned  terra  cotta  tile  of 
uniform  quality,  deeply  scored,  free  from 
shrinkage  cracks,  with  true  beds,  and  having 
an  ultimate  compressive  strength  of  4000  lbs. 
per  square  inch  of  the  net  area  of  surface 
tested. 

The  following  unit  stresses  and  values  shall 
not  be  exceeded.  Compression,  extreme  fiber 
stress  on  tile  500  pounds  per  square  inch. 
Shearing  stress  on  tile  200  pounds  per  square 
inch.  Adhesion  between  tile  and  1:2;  4 con- 
crete to  1 :3  mortar,  40- pounds  per  square  inch. 

Ratio  of  modulus  of  elasticity  of  steel  to  that 
of  tile  with  cement  mortar  joints,  10. 

(b)  Workmanship.  The  hollow  tile  shall 
be  thoroughly  drenched  with  water  at  the  time 
the  concrete  is  poured.  The  lines  of  tile  shall 
be  true  and  the  joints  between  tiles  shall  be 
staggered. 

Sec.  10.  Girderless  Floor.  By  girderless 
floors  is  meant  a type  of  reinforced  concrete 
construction  in  which  the  columns  are  pro- 

8 


vided  with  flaring  heads  and  the  loads  are 
carried  directly  to  the  columns  by  the  slab  and 
not  through  beams  and  girders.  • 

The  bending  moment  at  the  center  of  the 
slab  shall  not  be  less  than  WL/30  where 
“W”=total  load  on  panel  and  “L”=length  in 
feet  of  the  side  of  a square  panel  and  of  the 
side  of  an  equivalent  square  in  rectangular 
panels.  This  length  shall  be  taken  center  to 
center  of  columns.  The  steel  to  resist  this 
moment  shall  be  divided  into  four  bands,  two 
in  cross  and  two  in  diagonal  direction  over  the 
column  head. 

Each  band  of  steel  shall  be  approximately 
7/16  L in  width  and  the  total  amount  of  steel 
in  any  one  band  shall  not  exceed  .30  of  1 per 
cent  for  high  carbon  and  .36  of  1 per  cent  for 
medium  steel.  In  determining  the  percentage 
of  steel,  the  width  of  concrete  band  so  consid- 
ered shall  not  exceed  the  width  of  band  of 
steel  plus  twice  the  thickness  of  the  slab. 

All  splices  shall  be  made  at  the  column 
heads  and  the  amount  of  lap  of  each  bar  shall 
be  approximately  one-fourth  L (J^L).  At 
least  50  per  cent  of  all  the  bars  shall  be  spliced 
over  each  column.  In  this  construction  provi- 
sion shall  be  made  to  take  care  of  the  circum- 
ferential stresses.  Proper  provisions  shall  be 
made  for  resisting  the*  shear  at  the  capital  and 
for  holding  the  steel  in  the  proper  position  over 
the  column  head. 

The  diameter  of  the  column  head  shall  never 
be  less  than  .25L  and  its  profile  shall  not  fall 
inside  of  a line  drawn  from  its  periphery  to  the 
edge  of  the  column  and  making  an  angle  of 
45  degrees  with  the  vertical.  The  spiral  rein- 
forcing of  the  column  shall  extend  into  the 

9 


capital  approximately  to  the  under  side  of  the 
slab. 

The  minimum  thickness  of  the  slab  shall  be 
seven  (7)  inches  for  floors  and  six  and  one- 
half  (6 J4)  inches  for  roofs. 

In  end  panels  or  wall  panels,  in  which  wall 
columns  of  reinforced  concrete  “with  flaring 
heads  are  omitted  an  allowance  of  ten  (10) 
per  cent  shall  be  made  for  increased  moments. 
Wall  columns  shall  be  designed  to  carry  one- 
half  the  panel  load  and  such  other  loads  as 
may  come  upon  it,  and  if  necessary  the  col- 
umns shall  be  designed  for  eccentric  stresses. 
The  wall  beams  shall  be  designed  for  one-third 
the  panel  load  plus  any  other  loads  which  may 
come  upon  them. 

Sec.  11.  Web  Stresses.  Shear  on  concrete 
shall  not  exceed  one  hundred  and  twenty  (120) 
pounds  per  square  inch,  but  where  said  shear 
exceeds  fifty  (50)  pounds  per  square  inch,  web 
reinforcement  of  approved  design  shall  be  used. 
The  reinforcement  shall  be  designed  to  take  all 
web  stresses  in  excess  of  fifty  (50)  pounds  per 
square  inch,  without  exceeding  the  unit  stresses 
hereinbefore  given,  and  must  be  so  spaced  as 
to  intersect  any  45  degree  line  of  rupture  from 
the  neutral  axis  to  the  center  of  the  steel. 
Where  unattached  stirrups  are  used,  they  shall 
pass  under  the  main  reinforcing  bars.  At- 
tached stirrups  shall  have  connections  of  suf- 
ficient strength  to  develop  the  elastic  limit  of 
the  steel  without  slipping  along  or  shearing 
from  the  main  bars.  All  web  reinforceing 
shall  be  provided  with  sufficient  anchorage 
above  the  neutral  axis  to  develop  the  safe 
strength  of  the  member  without  exceeding  the 
bond  stresses  hereinbefore  given.  In  comput- 
ing the  intensity  of  the  vertical  shear  only  the 
area  of  the  web  between  the  center  of  grav- 

10 


ity  of  the  steel  and  the  center  of  compression 
of  the  concrete  shall  be  considered  as  effective. 

Sec.  12.  Protection  Against  Fire  and  Cor- 
rosion. All  reinforcing  steel  shall  be  protected 
by  concrete  of  the  following  minimum  thick- 
ness: Two  (2)  inches  in  columns,  one  and  one- 
half  (1J4)  inches  for  beams  and  girders,  and 
three-fourths  ($4)  inches  in  slabs. 

Sec.  13.  Reinforced  Concrete  Columns. 

Reinforced  concrete  columns  shall  not  exceed 
in  length  fifteen  (15)  times  the  least  diameter 
of  the  column,  including  the  reinforcement,  and 
where  such  ratio  is  more  than  twelve  (12) 
times,  the  stresses  shall  be  reduced  in  accord- 
ance with  the  best  engineering  practice.  In 
computing  the  strength  of  columns  only  the 
area  within  the  limits  of  the  ties,  bands,  hoop- 
ing or  spirals  shall  be  considered  as  effective 
area.  The  concrete  which  must  in  all  cases 
be  provided  outside  of  the  ties,  bands,  hooping 
or  spirals  as  provided  in  Section  12,  shall  be 
considered  only  as  protection  against  fire  and 
corrosion.  No  reinforced  concrete  column 
shall  be  used  whose  least  side  or  diameter, 
including  the  protection  against  fire  and  corro- 
sion, is  less  than  twelve  (12)  inches. 

Wall  columns  and  other  columns  subject  to 
eccentric  loads  of  and  indeterminate  amount 
shall  have  the  stresses,  as  hereinbefore  given, 
reduced  by  twenty  (20)  per  cent.  Eccentric 
loads  of  determinate  amount  shall  be  computed 
according  to  accepted  theory,  but  in  no  case 
shall  the  sum  of  the  stresses  due  to  direct  and 
eccentric  loads  exceed  the  maximum  stresses 
hereinafter  given  for  each  type  of  column. 

Sec.  14.  Square  Core  Columns.  In  the 

square  core  type  of  columns,  where  four  rods 
are  used,  and  the  minimum  area  of  each  rod 

11 


is  not  less  than  .4418  of  a square  inch,  and  the 
total  area  of  the  rods  is  not  less  than  one-half 
(y 2 ) and  not  more  than  four  (4)  per  cent  of 
the  required  area  of  the  column,  and  the  max- 
imum tie  spacing  does  not  exceed  twelve  (12) 
inches,  and  in  no  case  more  than  one-half  the 
distance  between  two  of  the  vertical  rods,  and 
the  minimum  area  of  the  ties  is  at  least  .0625 
of  a square  inch,  the  following  values  shall  not 
be  exceeded: 

7000  pounds  per  square  inch  on  the  vertical 
steel. 

500  pounds  per  square  inch  on  the  concrete. 

In  the  square  core  type  of  column,  where 
eight  rods  are  used  and  the  minimum  area  of 
each  rod  is  not  less  than  .4418  of  a square  inch, 
and  the  total  area  of  the  vertical  rods  is  not 
less  than  one-half  (^)  of  one  per  cent  and  not 
more  than  fiv'e  (5)  per  ‘cent  of  the  required 
area  of  the  column,  and  the  maximum  tie  spac- 
ing does  not  exceed  twelve  (12)  inches  and  in 
no  case  more  than  seven  (7)  times  the  diam- 
eter of  the  vertical  rods,  and  the  minimum 
area  of  the  ties  is  at  least  .0625  of  a square  inch, 
and  two  sets  of  ties  are  used,  one  in  the  form 
of  a square  inscribed  within  the  outer  tie;  and 
the  ends  of  the  ties  secured  in  such  a manner 
as  will  fully  develop  the  elastic  limit  of  the 
ties;  the  following  values  shall  not  be  ex- 
ceeded : 

9000  pounds  per  square  inch  on  the  vertical 
steel. 

600  pounds  per  square  inch  on  the  concrete. 

Sec.  15.  Round  Core  Columns.  For  round 
core  columns  vertically  reinforced  and  hooped 
with  circular  bands  or  spirals,  the  vertical  rods 
shall  not  be  less  than  four  (4)  in  number,  nor 
the  area  of  the  cross  section  of  each  rod  less 

12 


than  .4418  of  a square  inch,  nor  the  maximum 
spacing  of  the  verticals  more  than  twelve  and 
one-half  (12 1/2)  inches  measured  on  the  cir- 
cumference of  the  spiral,  the  percentage  of 
spiral  hooping  shall  not  be  less  than  one-half 
of  one  per  cent  and  not  more  than  one  and  one- 
half  (1 1/2)  per  cent  of  the  area  within  the 
hooping,  the  spacing  of  the  spirals,  if  such  are 
used,  shall  not  exceed  one-seventh  (1/7)  of  the 
diameter  of  the  core  and  in  no  case  more  than 
three  (3)  inches.  Provided,  however,  that  in 
cases  where  properly  welded  bars  are  used  and 
there  are  enough  vertical  rods  of  the  proper 
area  to  give  the  same  restraint  as  a grill,  the 
spacing  of  the  bands  shall  not  exceed,  for  the 
values  hereinafter  given,  seven  (7)  times  the 
diameter  of  one  such  vertical  rods. 

The  following  values  shall  not  be  exceeded 
for  either  of  the  foregoing  conditions : 

10,000  pounds  per  square  inch  on  the  vertical 
steel. 

700  ponds  per  square  inch  on  the  concrete. 

10,000  pounds  per  square  inch  on  2.4  times 
the  volume  of  the  spirals  considered  as  imag- 
inary verticals,  provided  that  the  spirals  are 
continuous,  machine  made,  provided  with  ac- 
curate spacers  and  secured  at  every  intersec- 
tion. 

Provided,  however,  that  if  wire  hooping  is 
used  not  less  than  five-sixteenth  (5/16)  of  an 
inch  in  diameter  (of  80,000  pounds  ultimate 
strength  and  50,000  pounds  elastic  limit)  an 
allowance  of  twelve  thousand  pounds  per 
square  inch  may  be  used  for  hooping,  provided 
that  whenever  such  value  is  allowed,  said 
spirals  shall  be  continuous,  machine  made,  and 
provided  with  accurate  spacers  and  secured  at 
every  intersection. 


13 


Sec.  16.  Column  Splices.  All  vertical  re- 
inforcing in  columns  shall  be  spliced  in  such 
manner  as  will  transmit  the  stresses  for  which 
it  is  designed.  Sharp  bends  in  the  steel  shall 
be  avoided.  The  splicing  of  verticals  having 
an  area  of  less  than  one  and  one-fourth  (1*4) 
square  inches  may  be  done  by -lapping,  the 
lapped  bars  to  be  wired  securely  to  each  other. 
Verticals  having  an  area  in  excess  of  one  and 
one-fourth  square  inches  shall  be  spliced  by 
putting  the  bars  squarely  one  over  the  other, 
and  tying  the  same  together  by  some  mechan- 
ical means  that  will  not  utilize  the  adhesive 
strength  oT  the  concrete.  All  splices  shall 
occur  only  at  floors  or  some  other  means  of 
lateral  support. 

Sec.  17.  Tension  in  Columns.  In  tall  nar- 
row buildings  special  provisions  shall  be  made 
for  tension  in  columns. 

Sec.  18.  Additional  Stories.  Where  addi- 
tional stories  are  to  be  added  to  work  over 
two  years  old,  the  strength  of  the  concrete  in 
the  existing  columns  may  be  taken  fifteen  (15) 
per  cent  higher,  than  the  values  herein 
specified. 

Sec.  19.  Footings.  Footings  for  walls  and 
columns  may  be  constructed  of  reinforced  con- 
crete, providing  the  working  stresses,  as  given 
in  this  code,  for  concrete  and  steel  are  not 
exceeded,  and  the  steel  is  protected  by  at  least 
three  (3)  inches  of  concrete. 

The  vertical  rods  in  reinforced  concrete  col- 
umns shall  be  anchored  to  the  footings  by 
anchor  bars  or  other  means  satisfactory  to  the 
Inspector  of  Buildings. 

Sec.  20.  Reinforced  Concrete  Curtain  Walls. 

Exterior  and  interior  walls  of  reinforced  con- 

14 


crete  shall  be  not  less  than  eight  (8)  inches 
thick  and  reinforced  with  not  less  than  three- 
tenths  (3/10)  of  one  per  cent  of  steel  in  each 
direction,  vertically  and  horizontally.  Rods 
shall  be  spaced  not  more  than  twelve  (12) 
inches  on  centers  and  shall  be  wired  to  each 
other  at  each  intersection. 

Sec.  21.  Cement.  Only  Portland  cement 
shall  be  used  which  conforms  to  the  standard 
specifications  of  the  Society  for  testing  ma- 
terials. All  cement  shall  be  tested  in  lots  of 
not  more  than  one  carload,  and  the  Department 
of  Buildings  may  at  any  time  demand  that  cer- 
tified copies  of  all  test  records  be  submitted 
for  examination. 

The  minimum  requirements  for  tensile 
strength  for  briquette  one  (1)  inch  square  in 


section  shall  be : 

NEAT  CEMENT. 

24  hours  in  moist  air 175  pounds 

7 days  (one  day  in  air,  six  in 

water)  500  pounds 

28  days  (one  day  in  air,  twenty- 

seven  in  water) 600  pounds 


ONE  PART  CEMENT,  THREE  PARTS 

SAND. 

7 days  (one  day  in  air,  six  in 

water)  175  pounds 

28  days  (one  day  in  air,  twenty- 

seven  in  water) 275  pounds 

Sec.  22.  Sand.  Fine  aggregate  shall  con- 
sist of  a mixture  of  fine  and  coarse  grains  of 
clean,  natural  sand,  screened  to  pass  a one- 
fourth  inch  screen,  with  the  coarse  grains  pre- 
dominating. Sand  shall  be  composed  of  hafrd 

15 


silicious  particles,  free  from  all  decomposed 
materials,  loam  or  other  deleterious  matter. 

Sec.  23.  Aggregate.  Coarse  aggregate 
shall  consist  of  crushed  stone  or  washed  gravel. 
It  shall  pass  through  a one  (1)  inch  screen  and 
be  retained  on  a one-fourth  {%.)  inch  screen, 
preferably  graded  from  small  to  large  particles. 
Crushed  stone  shall  be  reasonably  free  from 
crusher  dust.  The  particles  composing  the 
aggregate  shall  be  clean,  hard,  durable  and  free 
from  all  decomposed  materials,  loam  or  other 
deleterious  matter. 

Sec.  24.  Proportions  for  Mixing  Reinforced 
Concrete.  Reinforced  concrete  shall  consist  of 
a mixture  of  one  part  Portland  cement  to  not 
more  than  four  (4)  parts  aggregate  fine  and 
coarse  either  in  proportion  of  one  part  cement 
to  two  parts  sand  and  four  parts  aggregate,  or 
in  such  proportion  that  all  voids  in  the  aggre- 
gate shall  be  properly  filled. 

Mixing  shall  be  done  by  approved  batch 
mixer,  unless  the  conditions  of  the  work  would 
make  hand  mixing  preferable ; hand  mixing 
shall  be  done  only  under  the  approval  of  the 
Department  of  Buildings.  Enough  water  shall 
be  added  to  the  mixture  to  make  it  a plastic 
mass  capable  of  being  rammed  into  all  parts 
of  the  mould  and  around  all  reinforcing  mem- 
bers. In  all  mixing  the  separate  ingredients 
shall  be  measured  and  thoroughly  mixed  to  a 
uniform  color,  appearance  and  consistency  be- 
fore placing.  Thirty  days  after  mixing,  the 
concrete  shall  develop  a compressive  strength 
of  2000  pounds  per  square  inch  by  testing  a 
six-inch  cube. 

Sec.  25.  Bending  and  Elongation  of  Steel. 

The  reinforcing  steel  used  in  reinforced  con- 
crete construction  shall  conform  to  the  follow- 
ing requirements : 


16 


The  Inspector  of  Buildings  may  require  cer- 
tified tests  of  each  size  of  bar  used  in  the  con- 
struction, said  test  to  be  acceptable  for  not 
more  than  ten  tons  of  material. 

The  tests  for  bending  may  be  made  on  the 
ground  under  the  supervision  of  the  Inspector 
of  Buildings  or  his  authorized  assistant. 

17 


Sec.  26.  Placing  Concrete  and  Steel.  All 

reinforcement  shall  be  free  from  paint,  loose 
rust,  scale  or  coating  of  any  character  that 
would  tend  to  destroy  the  bond.  Steel  must 
be  accurately  located  and  secured  against  dis- 
placement before  concrete  is  poured  around 
it.  All  concrete  shall  be  tamped  in  place 
within*  one-half  (J4)  hour  after  mixing,  and 
shall  be  conveyed  in  place  in  such  a manner 
that  no  appreciable  separation  of  the  ingredi- 
ents occurs.  Concrete  must  be  worked  con- 
tinuously with  suitable  tools  as  it  is  put  in 
place,  and  in  warm  weather  must  be  kept  moist 
for  at  least  seven  (7)  consecutive  days  after 
pouring.  Work  must  be  laid  out  so  that  par- 
tially set  concrete  will  not  be  subjected  to 
shocks  from  handling  or  wheeling  materials 
over  it. 

Where  it  is  not  possible  to  cast  the  entire 
structure  in  one  operation  the  work  shall  be 
stopped ; for  columns,  at  the  under  side  of  the 
girders;  for  girders,  at  a point  midway  be- 
tween supports  unless  a beam  should  occur 
at  this  point,  in  which  case  the  joint  should 
be  offset  a distance  equal  to  twice  the  width 
of  the  beam;  for  slabs  and  beams,  at  the  cen- 
ter of  the  span.  Under  no  circumstances  shall 
a joint  be  made  where  high  present  or  future 
shearing  stresses  may  occur.  The  plane  of  all 
joints  shall  be  made  at  right  angles  to  the 
direction  of  the  beam,  girder,  column  or  slab. 
When  work  is  resumed  the  joints  shall  be 
thoroughly  cleaned,  drenched  and  slushed  with 
neat  cement  mortar. 

Beams  and  girders  shall  not  be  constructed 
over  freshly  placed  columns  without  permit- 
ting a period  of  at  least  ten  (10)  hours  to 

18 


elapse  to  provide  for  the  shrinkage  in  the 
columns. 

The  longitudinal  steel  in  beams  and  girders 
shall  be  so  designed  that  there  is  a thickness 
of  concrete  between  the  separate  pieces  of  steel 
of  not  less  than  one  and  one-half  (1*4)  times 
the  maximum  sectional  dimensions  of  the  steel 
and  in  no  case  less  than  one  (1)  inch.  Some 
means  satisfactory  to  the  Inspector  of  Build- 
ings shall  be  used  to  hold  all  reinforcing  steel 
in  its  proper  position. 

Sec.  27.  Centering  and  Forms.  All  forms 
shall  be  substantially  built  and  secured  to  pre- 
vent movement  or  deflection  during  the  prog- 
ress of  the  work.  They  shall  be  tight  to  pre- 
vent leakage  of  the  concrete.  An  opening  shall 
be  left  at  the  bottom  of  all  column  forms  for 
removing  foreign  matter  and  adjusting  the 
steel,  and  said  openings  shall  not  be  closed 
until  just  before  the  concrete  is  poured.  Be- 
fore placing  the  concrete,  the  forms  must  be 
thoroughly  cleaned  of  all  chips,  .dirt,  old  con- 
crete and  other  foreign  matter.  Forms  shall 
not  be  removed  until  the  concrete  has  set  suf- 
ficiently to  safely  resist  all  stresses  to  which 
it  may  be  subjected.  Two  weeks  of  good  dry- 
ing weather  with  a temperature  above  60 
degrees  Fahrenheit  shall  be  taken  as  the  min- 
imum time  for  the  removal  of  forms  where 
the  concrete  will  support  only  its  own  weight. 
The  joists  and  lagging  may  be  removed  in 
not  less  than  ten  days,  providing  the  sheating 
under  the  slabs  is  properly  shored.  The  time 
of  removal  of  forms  and^shores  under  heavy 
beams  and  girders,  varies  with  the  design  and 
weather,  but  in  no  case  shall  they  be  removed 
in  less  than  three  (3)  weeks  after  pouring,  pro- 
viding the  beams  carry  their  own  weight  only. 
When  beams  and  girders  carry  construction 

19 


loads  from  above,  sufficient  shores  shall  be  left 
in  place  to  carry  the  loads  until  the  completion 
of  the  work.  If  sufficient  shores  are  provided 
to  support  the  loads  on  slabs  and  girders,  the 
column  forms  may  be  removed  in  not  less  than 
four  (4)  days.  M 

Sec.  28.  Placing  Concrete  in  Cold  Weather. 

When  concrete  is  placed  in  freezing  weather, 
the  material  must  be  heated  and  such  provi- 
sions made  that  the  concrete  can  be  put  in 
place  without  freezing.. 

The  use  of  frozen  lumpy  sand  or  aggregate 
depending  on  hot  wateir  used  in  mixing  to  thaw 
it  out,  will  not  be  permitted.  All  reinforced 
concrete  shall  be  kept  at  a temperature  above 
freezing  for  at  least  forty-eight  (48)  hours 
after  being  put  in  place.  All  forms  under  con- 
crete placed  in  freezing  weather  shall  remain 
until  all  evidences  of  frost  are  removed  from 
the  concrete  and  the  natural  hardening  of  the 
concrete  has  proceeded  to  the  point  of  safety. 

Sec.  29.  Inspection.  When  any  reinforced 
concrete  is  used  in  construction,  the  owner 
shall  provide  for  the  inspection  of  cement  and 
inerts  ^ as  required  by  this  ordinance.  Unless 
otherwise  authorized  in  writing  by  the*  In- 
spector of  Buildings,  the  owner  shall  also  pro- 
vide a special  inspector,  who  shall  be  on  the 
work  continually  during  the  building  and 
removing  of  forms  and  the  placing  of  concrete 
and  steel.  Said  special  inspector  shall  be 
acceptable  to  the  Inspector  of  Buildings,  and 
may  be  required  to  pass  an  examination  given 
by  said  Inspector.  He  shall  make  daily  reports 
to  the  Inspector  of  Buildings  of  the  progress 
of  the  work,  on  blanks  furnished  by  the 
department. 

Sec.  30.  Test  for  Safety.  Within  a reason- 

20 


able  time  after  erection,  and  before  the  build- 
ing is  occupied,  a -test  shall  be  made  of  the 
work  as  directed  by  the  Inspector  of  Buildings. 
For  such  test  the  floor  panels  selected  by  said 
Inspector  must  be  loaded  to  twice  the  com- 
puted live  load  and  must  sustain  this  load  for 
twenty-four  (24)  hours  without  undue  deflec- 
tion or  other  evident  signs  of  failure. 

Sec.  31.  When  to  Take  Effect.  This  ordi- 
nance shall  take  effect  and  be  in  force  from 
and  after  the  earliest  period  allowed  by  law. 

DAVID  T.  LOGAN, 

President  of  Council. 

Passed  April  7,  1913. 

Approved  April  7,  1913. 

GEORGE  J.  KARB,  Mayor. 

Attest : 

JOHN  T.  BARR,  Clerk. 


21 


i 


■ 


t;  ’*  r . 

r 


V 


% 


■ 


3 0112  077835210 


